These functions seek the start of the first section, and return the name of this
section;
this section is made the internal current section. These functions may be used
to
process a configuration file consisting of unknown sections, but where each
section has known entries. If there are no sections, the function returns NULL.

PxConfigFirstSection() works on the currently open configuration
file opened by PxConfigOpen(),
while
PxConfigFirstSectionCx() works on the configuration file indicated by
cx.